I want something like code below, but \"pythonic\" style or using standard library:
def combinations(a,b): for i in a: for j in b: y
These are not really "combinations" in the sense of combinatorics, these are rather elements from the cartesian product of a and b. The function in the standard library to generate these pairs is itertools.product():
a
b
for i, j in itertools.product(a, b): # whatever